Synchronizer



H. l. LARSON.

SYNCHRONIZER.

APPLICATION FILED IIov. a, 1919.

2 SHEETS-SHELT 1- Patented Apr. 19, 1921.

2k3/@fr u fo/Py fla/507D 8v M H. I. LAHSON.

SYNCHRONIZER.

APPLICATION FILED NOV. 3.19I9.

1,374,929. Patented Apr. 19, 192i.

2 SHEETSHSHEET 2.

MBH-7% UNITED STATES HENRY I. LMSON, OF MILWAUKEE, WISCONSIN.

SYNCHRONIZER.

Specication of Letters Patent.

Patented Apr. 19, 1921.

Application filed November 3, 1919. Serial No. 335,298.

To all w hom t ma 1/ concern Be it known that I, HENRY I. LAnsoN, a citizen of the United States, residing at Milwaukee, in the county of Milwaukee and State of W'isconsin, have invented ne-w and useful Improvements in Synchro-nizers, of which the following is a specification.

This invention relates to synchronizers.

It relates more particularly to synchronizers for use in systems in which a master clock controls the transmission of current impulses over a control or operating circuit for controlling electromagnetically operated secondary clocks, time recorders or other time indicators.

Current for operating the time indicators may be supplied from the ordinary lighting or power circuit or from a storage battery or dry cells. If for some reason trouble develops with the current supply current may be disconnected from the control or operating circuit of the time indicators for a period ranging from a few minutes to several hours. During the time that current is disconnected, the time indicators are not advanced by the continued movement of the master clock and therefore are not maintained in synchronism therewith. When the trouble is cleared and current is again connected with the control circuit, the time indicators are again advanced in the usual manner by current impulses transmitted over the control circuit during the movement of the master clock. The indicators are not however in synchronism with the master clock, but lag behind the master clock a distance determined by the length of time that current was disconnected from the control circuit. In order that the indicators of the system may be brought into synchronism with the master clock, it is necessary that v each be separately adjusted.

Time recorders, secondary clocks and other time indicators are employed where it is very desirable that they be maintained at all times in synchronism with the master clock, and if they get out of synchronism with the master clock, it is important that they be brought into synchronism therewith as quickly as possible. l

An object of this invention is to provide a synchronizer which will overcome the difliculties mentioned.

Another object of the invention is to prov ide a synchronizer which is common to the time indicators of the system.

Another object is to provide a synchronlzer whlch may be easily and quickly installed in existing time indicating systems.

A further object is to provide a synchronlzer Which will automatically restore the secondary clock movements to indicate the correct time and in synchronism With the master clock, after the secondary clocks have been ineffective for a period.

Other objects and advantages will appear from the following description.

In accordance with this invention there is provided a synchronizer which, upon the connection of current with the control circuit or circuits of the system in which it is employed, functions automatically to advance the time indicators a distance determined by the length of time that current Fig. 1.

Fig. 3 is a transverse section on line 3-8 of Fig. 2.

Fig. 4 is a. transverse section on line 4--4 of Fig. 2.

Fig. 5 is a transverse section on line 5--5 of Fig. 2 showing the contacts carried by the continuously driven disk.

Fig. 6 diagrammatically illustrates a time recording system in which the synchronizer is employed.

Fig. 7 is a perspective of a portion of the master clock mechanism equipped with a switch which may form part of the synchronizer.

The synchronizer, which may be mounted in the clock casing 10 housing the master clock, represented generally at 9, comp-rises a control member 13 responsive to the movement of the master clock, a pair of contacts 30 and 31 whoseengagement is controlled by the control member 13 and Whose disengagement is controlled by a second control member 14 intermittently actuated by amotor magnet 44 controlled by both members. The synchronizer may also include a sup-plementarypair of contacts actuated by a controlling electromagnet 60 or by the master clock and coperating with the other.' pair of contacts for controlling the operation of the secondary clocks or recorders. The two control members may, for the purposes of illustration. take the form of rotatable wheels or disks.

Referring to Figs. 1 and 2 the two disks 13 and 14 are loosely mounted upon a stud or arbor 15 projecting from a bearing plate. 16. This bearing plate 16 is carried by the rear wall 17 of the clock case 10 andA is spaced therefrom by suitable bushings 18 through which extend bolts for securing the bearing plate to the rear wall` of the clock case. The driving connection between the drive mechanism ofthe master clock and the disk 13 comprises a vertically disposed shaft 20 the upper end of which carries a bevel gear 21 meshino' with a second bevel gear 22 associated with the clock drive mechanism in any desired manner. The lower end of the vertically disposed shaft 2O is journaled in two lateral ears 23 and 24 of a forwardly extending bracket 25 mounted upon the bearing plate 16. The shaft 2O carries at its lower end a bevel gear 26 which meshes with a bevel gear 27 on one end of a horizontal shaft 28 journaled in the bracket 25. A pinion 29 carried by the rear end of the shaft 28 meshes with the teeth provided in the periphery of the disk 13. As the hands of the clock are advanced in a clock-wise direction, the connection between the clock and the disk 13 causes the disk 13 to be rotated in an anti clock-wise direction. The disk 13 carries a pair of contact arms 30 and 31 mounted upon an insulating plate 32 secured to the rear of the wheel 13. The contact arm 30 is pivoted at 34. A spring 33 (see Fig. 5) secured at one end to the insulating plate 32 and at its other to a projection 34 of the contact arm30 normally tends to maintain the contact arms in engagement.

Two collector rings 55 and 56 carried by and insulated from the rotatable disk 13 are electrically connected with the respective Contact arms 30 and 31. Contact ligures 57 and 58 mounted upon an insulating block 58 frictionally engage the periphery of the respective collector rings 55 and 56.

The driving mechanism for the disk 14 will now be described, reference being had to Figs. 2, 3 and 4.

A pinion 36 carried by the forward end i, ofa shaft 37 journaled in the bea-ring plate 16 meshes with the teeth of disk 14. Two ratchet wheels 38 and 39 are rigidly secured to the rear end of the shaft 37. A stepping pawl 40 carried by an arm or lever 41 pivoted on a pin 42 is adapted to engage the ratchet wheel 38 to cause the intermittent rotation of the shaft 37 A coil spring 43 secured at one end to a pin 43 and at its other to one end of the pivoted arm 41 normally maintains the stepping pawl 40 in engagement with the ratchet wheel 38. The other end of the pivoted arm 41 carries an armature 43 which is in operative relation to an electromagnet 44 mounted upon a bracket 45 secured to the rear of the bearing plate 16. A holding pawl 46 pivoted on a pin 47 is adapted to be thrown into engagement with the teeth of the ratchet wheel 38 whenever the stepping pawl 40 is moved out of engagement therewith. This holding pawl 46, therefore prevents backward movement of the ratchet wheel whenever the stepping pawl 40 is not in engagement therewith. The pivoted arm 41 carries a laterally extending lug 48 which engages the ratchet wheel 39 after the stepping pawl 40 engages the ratchet wheel 38 and prevents th-e advancement of the shaft 37 more than one step for each engagement of the vpawl 40 with the ratchet wheel 38. It is to be observed in this connection that the teeth on the two ratchet wheels 38 and 39 are cut in opposite directions.

The energization of the electromagnet 44 causes the attraction of the armature 43 which rocks the arm 41 about its pivot 42 against the action of the spring 43. The pivoted lever 41 thereupon moves the lug 48 out of engagement with the ratchet wheel 39 and also moves the stepping pawl 40 out of engagement with the ratchet wheel 38. The holding pawl 46 is moved into engagement with the ratchet wheel 38 just prior to the disengagement of the stepping pawl 4() therefrom.

Upon the denergization of the electromagnet 44, the spring 43 moves lthe pivoted arm 41 in the opposite direction about its pivot, causing the stepping pawl 40 to engage a tooth of the ratchet wheel 38 and advance the shaft 37 one step. Shortly after the engagement of the stepping pawl 40 with the ratchet wheel 38, the lug48 engages the ratchet wheel 39 to prevent more than a one step advancement upon each deenergization of the electromagnet 44. Each denergization of the electromagnet 44 therefore causes the one step advancement of the disk 14 in an anti clock-wise direction; that is, in the same direction that the disk 13 is rotated.

Normally the disks 13 and 14 are in such a position that a pin 48 carried by and insulated from the disk 14 engages the free end of the pivoted contact arm 30 'and holds it out of engagement with the contact arm 31.

As shown in Fig. 1, the controlling electromagnet 60 having a pivoted armature 61 is suitably mounted on an insulating plate 59 which may be secured to the rear wall 17 of the clock case. The armature 61 carries an insulated contact spring 62 adapted to engage acontact stud An arm 64 is pivoted to the upper end of t-he armature 61. One end of this pivoted arm 64 is provided with a dog 65 normally held in engagement with a ratchet wheel 66 by means of a spring 67 acting on the other end of the pivoted arm. A pin 68 carried by thev pivoted arm 64 extends through a slot 69 in the free end of an arm 70 flexibly mounted upon a block 71 by means of a leaf spring 72. A lever 73 pivoted on a pin 74 is provided with a dog 75 normally held in engagement with the ratchet wheel 66 by means of a coil spring 76. The lever 73 has a downwardly extending arm 77- having at its extremity a lateral ,extension 78. An adjustable contact screw 79 carried by this lateral extension 78 normally engages a laterally extending lug 8O provided on the resiliently supported arm 70. The leaf spring 72 is so biased that through its action the contact lug 80 exerts a downward pressure upon the contact screw 79. The ratchet wheel 66 is rotatably mounted upon a pin 81 in the plate 59. For retarding the movement of the ratchet wheel 66, a brake spring 82 supported by a block 83 has frictional engagement with the hub of the ratchet wheel. Terminals 84 and 85 carried by the plate 59 are provided for the electromagnet 60. The operating clrcuit. of the electromagnet 60 includes the terminal 84, coil spring 76, lever 73, arm 77 and lateral extension 78 thereof, contact screw 79, lug 80, Varm 70, leaf spring 72, conductor 86, winding of the electromagnet 60, conductor 87 and terminal 85.

When the: electromagnet 60 energizes, the armature 61 is attracted against the action of the coil Spring 88. Upon the movement of the armature, contact spring 62 engages contact 63, and the pivoted arm 64 is moved laterally. The dog 65 is in engagement with the ratchet wheel 66. During the lateral movement of the arm 64 therefore, the dog 65 rides along the face of the next tooth of the ratchet wheel, and the pin 68 moves along the inclined slot 69 in the free end of the resiliently supported arm 70. When the apex of the dog 65 reaches the apex of the tooth along the face of which it is moving, the further lateral movement of the arm 64 allows the spring 67 to move the arm 64 about its pivot quickly seating the dog 65 between the tooth along which it has been riding and the next tooth. When the dog 65 reaches the apex of the tooth along the face of which it was riding, the pin 68 is near the lower end of the inclined slot 69. Therefore when the dog 65 is moved in between the adjacent teeth, the pin 68 raises the arm 70, causing the disengagement ofthe contact screw 79 and the contact lug 80. The contact screw 79 and lug 8() are in the energizing or operating circuit of the electromagnet, so that upon the disengagement of these contacts, the electromagnet denergizes. The coil spring 88 thereupon restores the armature 61 to its normal position, causing the disengagement of contacts 62 and 63. Since the dog 65, during the forward movement of the armature, engaged another tooth of the ratchet wheel 66, it (the dog 65) during the backward movement of the armature rotates the ratchet wheel one step in a clock-wise direction. During this backward movement of the armature 61 the pin 68 is being moved horizontally, allowing the leaf spring 72 to lower the arm 70 and its contact lug 80, at the same time, the dog 75 is riding along the face of a tooth on the ratchet wheel 66 and is moving the lever 73 about its pivot 74 in an anti clock-wise direction and is consequently lowering the lateral extension 78 and the contact screw 79 carried thereby. The contact lug 80 and screw 79 are being lowered simultaneously so that they are maintained out of engagement until the armature 61 has almost reached its normal position and the contacts 62 and 63 have disengaged. When fthe armature 61 almost reaches its normal position, the ratchet wheel 66 has rotated suficiently to allow the spring 76 to rotate the lever 73 about itspivot'in the opposite direction and seat the dog 75 between the next two teeth. As the dog is being so seated the contact screw 79 is raised into engagement with the contact lug 80.

Fig. 6 shows the circuits of a time recording system with which the synchronizer including the control magnet 60 is associated. For convenience in describing the operation of the system, many details of the synchronizer are omitted from this figure, the constantly driven and intermittently driven disks 13 and 14, the collector rings 55 and 56, the control relay 60 and the actuating or motor magnet 44 for the intermittently driven disk being sho-wn in skeleton form. A conductor 90 connects the contact arm 30 carried by the constantly driven disk 13 with the collector ring 56, while a conductor 91 connects contact arm 31 with collector ring 55. A conductor 92 connects collector brush 57 with contact 8() of control relay or magnet 60, while conductor 93 connects collector brush 58 with one pole of a suitable source of current, such as an ordinary lighting or power circuit, represented by the line conductors 1 and 2 which, it will be understood, are connected with a source of current. The other pole of the source of current or conductor 2 is connected through a limiting resistance 94 and conductors 95 land 95a with the winding of control relay or magnet 60 and contact spring 62 thereof.

The time recording system may include a plurality of time recorders, secondary clocks or other time indicators controlled from a master clock and maintained in synchronism therewith by means of the synchronizer. These time recorders, secondary clocks or other time indicators, may be of any well known type and may be connected in the system .in any well known manner. For convenience, only recorders are represented in the drawing, but it will be understood that secondary clocks maybe controlled in the same manner as the recorders.

The recorders are represented generally at 100, 100, 100", etc. Each recorder comprises well known character carrying dlsks which may be actuated by the armature of the motor magnet through a pawl and ratchet or in any other well known manner.

The windings of the motor magnets of the recorders are connected in series with the winding of the motor magnet 44 of the intermittently driven disk 14. A conductor 96 connects the contact 63 of the control magnet 60 with the windings of the motor magnet 44 and the electromagnets 105, 105, 105), etc., while the conductor 97 connects these windings with the positive terminal of the source of current.

The operation of the system illustrated in Fig. 6 and equipped with the synchronizer will now be described.

N ormally, the contact arms 30 and 31 are held out of engagement by the pin 48 carried by the disk 14. The wheel or disk 13 is continuously driven by the master clock in the direction of the arrow. The gear ratios are such that in one minutes time the wheel 13 is advanced from a given position sufliciently far to permit engagement of the contact arms 30 and 3l. Upon the engagement of these contact arms an operating circuit for the magnet 60 is completed from line conductor l through conductor 93, brush 58, collector ring 56, conductor 90, contact arm 30, contact arm 31, conductor 91, collector ring 55, brush 57, conductor 92, contact lug 80, contact screw 79, winding of the electromagnet 60, conductor 95, i'esistance 94 to the line conductor 2. Electromagnet 60 thereu on energizes, attracting its armature61. "ontact spring 62 engages contact 63 closing the operating circuit for the motor magnet 44, and the recorder motor magnets 105, 105, 105, etc. This circuit may be traced from line conductor 1 through conductor 97,'the windings of the electromagnets 105D, 105a`, and 105, the winding of the motor magnet 44, contact 63j, contact spring 62, conductor 95a 94, line conductor 2. 4The motor magnets in this circuit are energized and attract their armatures. The armatures the recorder magnets cause the pawls to engage thek ratchet wheels for advancing the and resistance associated with character carrying disks of the recorders one step. The attraction of the armature associated with the motor magnet 44 moves the arm 41 about its pivot 42 moving the stepping pawl 40 out of engagement with the ratchet wheel 38.

The attraction of the armature 61 of the' magnet 60 after causing contact spring 62 to engage contact 63 as previously described causes contact screw 79 and contact lug 80 to disengage, opening the operating circuit of the magnet 60. This magnet 60 thereupon denergizes and its armature 61 restores to normal position. During the restoration of this armature 61 to its normal position, contact spring 62 disengages contact 63 after which contact screw 79 and contact lug 80 engage. Upon the disengagement of contacts 62 and 63, the operating circuit for the motor magnet 44 and the recorder motor magnets is opened whereupon these magnets denergize. The denergization of the motor magnet 44 allows the spring 43 to move the arm 41 about its pivot 42 thereby causing the stepping pawl 40 to engage the ratchet wheel 38 and move it one step. The pinion 36 rotates with the ratchetwheel 38 so that the intermittently driven disk or Awheel 14 which meshes with the pinion 36,

is advanced one step due to the one step advancement of the ratchet wheel 38. This movement of the wheel 14 is sufiicient to cause the pin 48 carried thereby to engage and move contact arm 30 out of engagement with contact arm 31. This contact arm 30 is moved out of engagement with contact 3l prior to the engagement of the contact screw 79 and contact lug 80 so that upon the engagement ofthe contact screw and lug the controlling magnet 60 is not renergized.

The denergization of the recorder motor magnets allows the armatures thereof to resume their normal positions whereby each pawl is moved into engagement with the next tooth of its ratchet wheel preparatory to advancing t-he character controlling disks.

f current is disconnected from thecontrolling circuits when the contact arms 30 and 31 engage then the controlling electromagnet 60 will not be energized and the recorders will not be advanced, nor willthe intermittently driven disk 14 be advanced. As previously explained, current may be disconnected from the controlling circuits due to any one of several causes and may remain disconnected therefrom for a period ranging from a vfew minutes to several hours. During this. time that current is disconnected from the. controlling circuits, the disk 13 contmues to rotate due -to'the driving connection with the master 'clock and contact arms 30 and 31 engage and remain in engagement.` During this time however, intermittently'actuated disk 14 remains staeffective. Upon the'reconnection of current with the controlling circuits controlling electromagnet 60 is immediately energized and functions in the manner previously described to cause the motor magnet 44 to advance the intermittentlydriven disk 14 one step and the recorder motor magnets to advance the character carrying disks one step. If current was disconnected from the controlling circuits for more than one minute then the advancement of the disk 14 one step will not cause the pin 48 to engage the contact arm 30. Therefore, the rengagement of the contact screw 79 and the contact lug 80 following the denergization of the controlling magnet 60 causes the renergization of the controlling magnet which again functions in the manner previously described to cause the operation of the motor magnet 44 and the recorder motor magnets. The controlling electromagnet 60 will continue to function causing the advancement of the intermittently actuated disk 14 until the pin 48 carried thereby engages contact arm 30 and moves it out of engagement with contact arm 31. While the intermittently driven disk 14 was being advanced tothis point the recorders were also being advanced, so that when contact arm 30 is movedsout of engagement with the contact arm 31, the recorders are again in synchronism with the master clock. Thereafter while current is connected with the controlling circuits the contact arms 30 and 31 engage once every minute whereupon the controlling electromagnet functions to cause the operation of the motor magnet 44 and the recorder motor magnets.

Fig. 7 shows a portion of the master clock mechanism equipped with a contact making device which may be employed in place of the controlling electromagnet 60 for coperating with the disks 13 and 14 to control the recorders. This portion of the master clock mechanism includes the usual verge shaft 110 carrying a verge 111 actuated by a verge wheel 112 mounted upon the shaft 113. This shaft 1131 is constantly driven in the usual manner from the driving vmechanism of the master clock and through the connection between the verge wheel 112 and the verge 111 the shaft 110 is oscillated to control the movement of the pendulum 114 with which the shaft 110 is loosely connected by the L-shaped arm 115.

A contact arm 116 carried by and insulated from the verge shaft 110 is adapted to engage a stationary contact 117 each time that the pendulum swings to the left. Conductors 118 and 119 may be connected with the contact arm 116 and the contact 117.

The Contact arm 116 and the contact 117 may be connected in the controllin circuits of the time recorders shown in ig. 6 in place of the electromagnet 60 for coperating with the disks 13 and 14 vto maintain the` tnne recorders in synchronism with the mast@ clock. When making the substitution, that portion of the apparatus and conductors shown within the dotted rectangle 124 removed, and the contacts 116 and 117 are lnscrted between the negative line terminal 2 and conductor 93 by connecting conductor 118 at the point 122 and the conductor 119 with conductor 93 at the point 123, while the conductor 92 is connected directly with conductor 96-between the points 12() and 121. When the contact arm 116 and the contact 117 are substituted for the controlling electromagnet 60 in this manner the control or operating circuit for the motor magnets includes limiting resistance 94, conductor 118, contact arm 116,'contact 117, conductors 119 and 93, brush 58, collector ring 60, conductor 90, contact arm 30, contact arm 31, conductor 91, collector ring 55, brush 57, conductors 92 and 96, windings of the motor magnet 44 andthe recorder motor magnets 105,l 105, 1051, etc., and conductor 97. Therefore when the disk 13 has been advanced sufficiently far to allow the contact arms 30 and 31 to engage then upon the .next engagement of the contact arm 116 with the contact 117 the operating circuit for the motor magnet 44 and the 95 recorder motor magnets 105, 105a, 105", etc.,

is closed and these motor magnets function in the manner previously described. The motor magnet 44 upon energizing, causes the pivoted arm 41 to move the stepping pawl 100 40 out of engagement with the ratchet wheel 38. The swing of the pendulum 114 in the opposite direction moves the contact arm 116 out of engagement with the contact 117 thereby opening the operating circuit and 105 lcausing the denergization of the motor magnets. The spring 43 thereupon swings the arm 41 about its pivot causing the stepping pawl 40 to engage the ratchet wheel 38 thereby advancing the intermittently 110 actuated disk 14. The pin 48 carried by this disk 14 engages contact arm 30 and moves it out of contact with the arm 31, so that the operating circuit is open when the contact arm 116 neXt engages Contact 117.

By employing the described synchronizer in a time recording system in which the recorders get out of synchronism with the master clockwhile current is disconnected from the system, the synchronizer functions 120 immediately upon the connection of current with the system to bring the recorders into synchronism with the master clock. When the recorders have been thus brought into s chronism with the master clock, the sync ronizer restores to its normal condition ready thereafter to advance the recorders minute by minute in accordance with the movement of the master clock.

This synchronizer which is of few parts may be installed very. quickly in existing recording' systems. Such recording systems may therefore be made more useful by the addition thereto of these synchromzers, only one being required for each system.

The drawings and descrlption thereof are to be considered in merely an illustrative and not in a limiting sense for it is obvlous that other structures lmay be devised Which will embody the invention.

lVliat is claimed is:

1. In al synchronizing system in which a master clock 'controls the regular periodic transmission of current impulses tokeep time yindicators in step therewith, electromagnetic means responsive solely to the restoration of electric power to the lsystem after failure thereof` thereby to transmit rapidly current impulses to bring the indicators quickly into synchronism with the master clock.

2. In a synchronizing system in which a master clock controls the vregular periodic transmission of current impulses to keep time indicators in step therewith, a synchronizer having electromagnetic means responsive solely to the restoration of electric power to the system after a period of failure thereof, thereby to transmit rapidly and independently of the movement of the master clock current impulses to bring the indicators into synchronism with the master clock.

3. A synchronizer for use in time indicating systems in which a master clock controls electromagnctically operated time indicators, comprising a member adapted to be driven constantly by the master clock, a second member, a motor magnet for intermittently driving the second member, a pair of contacts carried by one of said members, and means carried by the other member for controlling the engagement of said contacts whereby said contacts control the operation of the indicators.

4. A synchronizer for use in time indicating systems in which a master clock controls electromagnetically operated time indicators, comprising a member-adapted to be driven constantly by the master clock, a motor magnet, a second member intermittently driven by the motor magnet, a pair of contacts whose engagement is controlled by one member and whose disengagement is controlled by the other member, the contacts being movable with one of the members, and an operatin circuit for the indicators controlled by t e contacts.

5. A synchronizer for use in time indicating systems in which a master clock controls electromagnetically operated time indicators, comprising a member adapted to be controlled in its movement by the master clock, a, motor magnet responsive to the movement of said member, a second member controlled by the motor magnet, and a pair of contacts movable with one member and controlled by both members for causing the operation of the indicators..

6. A synchronizer for use in time indicating systems in which a master clock controls electromagnetically operated time indicators, comprising a control member adapted to be responsive to the movement of the master clock, a second controlling member, an

` actuating motor magnet therefor, and a pair of contacts movable with the first member and controlled by both members for controlling the operating circuits of the indicators.

7. In a 'synchronizer for use in time indicating systems in which a master clock ccntrols electromagnetically actuated time indicators, comprising a controller to be driven from the master clock, a motor magnet and va controller driven intermittently thereby,

and a pair of contacts movable with the clock driven controller, the engagement of the contacts being effected by the clock driven controller and the disengagement thereof by the motor driven controller.

8. A synchronizer for use in time indicating systems in which a master clock controls electromagnetically operated time indicators, comprising a controller to be driven constantly from the master clock, a motor magnet and a controller driven intermittently thereby, and a pair of contacts movable with the clock driven controller, the closure of the contacts being effected by one controller and the opening thereof by the other.

9. A synchronizer for maintaining electromagnetically actuated time indicators iny synchronism with a master clock, electromagnetic means controlling the movement of the indicators and responsive to the restoration of power to the synchronizer after a period of ineffectiveness thereof to cause, independently of the then condition of the master clock, the rapid advancement of the indicators into synchronism with the masg ter clock.

10. In a synchronizer for maintaining electromagnetically actuated time indicators 1n synchronism with a master clock, electromagnetic means controlling the movement of the indicators and responsive to and dependent solely upon the restoration of power to the synchronizer after a period of ineffectiveness thereof to cause the rapid advancement of the indicators into synchronism with the master clock. i D 1 1. A synchronizer for maintaining time indicators in synchronism with the master clock comprising a constantly driven member and an intermittently driven member' adapted to be controlled by the master clock, a pair of contacts carried by the constantly driven member, means carried by the intermittently driven member' controlling the engagement of the contacts, an electromagnet having an operating circuit controlled by the engagement of the contacts, and means controlled by the electromagnet for actuating the indicators.

12. A synchronizer for maintaining time indicators in synchronism with the master clock comprising a constantly driven member and an intermittently driven member adapted to be controlled by the master clock, a pair of contacts carried by one member, means carried by the other member controlling the engagement of the contacts, an electromagnet having an operating circuit controlled by the contacts, and means controlled by the electromagnet for actuating the indicators.

13. A synchronizer for maintaining time indicators in synchronism with a master clock comprising a constantly driven controller and an intermittently driven controller, a pair ofY contacts movable with the constantly driven controller and intermittently closed by advancement thereof and opened by the advancement of the other controller, and electromagnetic means responsive to the restoration of power to the synchronizer and cooperating with the controllers to cause said contacts to transmit rapidly current impulses for quickly restoring the indicators to synchronism with the master clock.

14. A synchronizer for maintaining time indicators in synchronism with a master clock comprising a continuously driven controller responsive to the master clock, a normally closed circuit closer movable with said controller, an intermittently movable controller adapted to periodicall open said circuit closer while said time inc icators are in synchronism with the master clock, but to permit said circuit closer to remain closed to automatically advance and restore the indicators to synchronism with the -master clock upon restoration of power to the indicator.

15. A synchronizer for maintaining time indicators in synchronism with a master clock comprising a continuouslyv driven control member responsive to the master clock, anintermittently driven control member, a pair of contacts movable with one of the members and controlling the circuit of the time indicators, and means cooperating with the intermittently driven member to control the engagement of the contacts whereby the time indicators are automatically advanced and restored to synchronism with the master clock if the indicators have been ineffective for a given period.

n 15.A synchronizer for maintaining time mdicators in synchronism with a master clock comprising a continuously driven member mechanically actuated by the master clock, an intermittently driven member actuated by electromagnetic means, means cooperating with the first named member controlling the time indicators, and means associated with the intermittently driven member adapted to cause the time indicators to be intermittently advanced and maintained in synchronism with the master clock so long as electrical power is effective, and in case of failure'of power to cause the time indicators to be advanced and brought in synchronism with the master clock to indicate the correct time upon the restoration of power to the circuit.

17. A synchronizer for maintaining time i indicators in synchronism with a master clock comprising a continuously driven member mechanically actuated by the master clock, and an intermittently driven. member actuated by electromagnetic means, the intermittently driven member cooperating with the continuously driven member to automatically advance the time indicators to synchronism with the master clock upon restoration of power to the line.

In witness whereof I have hereunto subscribed my name.

HENRY I, LARSON. 

